Encapsulation:

ORACLE's Object Oriented implementation is based on a relational system. Within a relational system the means of accessing data is never fully limited. Therefore, data within the ORACLE cannot commonly be completely encapsulated.  The Encapsulation can be achieved through limiting access to tables and forcing all access to be accomplished by procedures and functions, but this avoid the realization of the true power of a relational database.

Polymorphism:

Polymorphism enables various objects to have methods through the similar name which accomplish same tasks, but in variant ways. An Oracle incorporates this feature in Packages through incorporating the concept of Method Overloading.